The present invention relates to a method for manufacturing a metal-oxide-semiconductor (MOS) structure which includes a silicon carbide (SiC) substrate and an oxide film deposited on the SiC substrate.
Silicon carbide (SiC) has a wide band gap (2.2 to 3.3 eV), and is thermally, chemically and mechanically stable, and also tolerant of radiation damage. Accordingly, SiC semiconductor devices such as transistors and diodes formed on an SiC substrate are expected to have stable operation even in a high temperature environment, under a high power operation, and while being exposed to the radiation.
On the other hand, a metal-oxide-semiconductor (MOS) structure is well known in the art, wherein an oxide film is formed on a semiconductor surface. Especially, MOS diodes, MOSFETs and MOSICs formed on a silicon substrate are widely used in the art.
Accordingly, if diodes, transistors of ICs of the MOS structure are effectively formed on the silicon carbide (SiC) substrate, advantages of the silicon carbide and the MOS structure will be combined. However, it is difficult to effectively form an oxide layer on a silicon carbide (SiC) semiconductor. If the conventional thermal oxidation method is employed to form the oxide layer on a silicon carbide (SiC) substrate, the oxidation rate is very slow, and a sharp boundary is not formed between the oxide layer and the silicon carbide (SiC) substrate. Generally, the MOS structure requires a well-insulating oxide layer of 500 through 2000 .ANG., which forms a sharp boundary between the semiconductor.
Accordingly, an object of the present invention is to provide a novel method for effectively forming a MOS structure on a silicon carbide (SiC) semiconductor substrate.
Another object of the present invention is to effectively form an oxide layer on a silicon carbide (SiC) semiconductor substrate.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a silicon thin-film is deposited on a silicon carbide (SiC) semiconductor. The silicon thin-film is oxidized to form an oxide layer on the silicon carbide (SiC) semiconductor. A metal electrode is disposed on the oxide layer (silicon oxide) to form the MOS structure. Since the oxidation process is conducted on the silicon thin-film, the oxidation is achieved in a short time and a sharp boundary is ensured between the SiC semiconductor. Furthermore, the thickness of the oxide layer is easily controlled by controlling the thickness of the silicon thin-film.